Technical data

6-24 User’s and Service Guide
Servicing the Test Set
Theory of Operation
A3 Controller Board (Mother Board) and Switch Driver Board
(Daughter Board) Theory
Refer to the block diagram, Figure 6-1 on page 6-22, for the following
discussion.
The mother and daughter boards provide the bias for the switching
paths for the various ports to the Transmission and Reflection ports.
The front panel display contains an LCD that indicates the switched
ports. A particular test port (1 through 16) can be in one of three states.
The three states are as follows:
• Switched to the forward path
• Switched to the reverse path
• Terminated in 50
Ω
When a port is not connected, it is automatically terminated in 50 Ω.
The test set consists of sixteen (16) 1 by 2 switches, six (6) 1 by 6
switches, and two (2) 1 by 4 switches. The 1 by 2 switches divide each of
the input ports (1 through 16) into two separate paths, the
Transmission path or the Reflection path.
Each path, Transmission or Reflection, connects to a bank of three (3)
1 by 6 switches (for a total of six (6) 1 by 6 switches). The 1 by 6
switches connect to a bank of two (2) 1 by 4 switches. Each bank of 1 by
6 switches connects to a single 1 by 4 switch where it connects to either
the Transmission or Reflection port.
All switches are mechanical, and are biased according to the necessary
switching path. A user interface through the GPIB and parallel ports
converts the necessary input signals from the user to the necessary
signals controlling the switching paths.